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DESCRIPTION
The Babiski response, or upgoing plantar response, is an abnormal cutaneous reflex response of the foot associated with upper moter neuron dysfunction. In a positive Babiski response, scratching the lateral plantar surface of the patient’s foot causes contraction of the extensor hallucis longus muscle and extension of the great toe ( normally the toe goes down)
CONDITION/S ASSOCIATED WITH
common
– cerebral infraction
– cerebral heamorrhage
– spinal cord injury
less common
– lacunar infarction, posterior limb internal capsule
– multiple sclerosis
– mass lesion ( tumour, abscess, AVM)
MECHANISM
Before 1 or 2 years of age, a noxious stimulus applied to the lower extremities cause involuntary ankle and foot dorsiflexion. The so-called ” flexion response” is a primitive reflex that disappears later in life. After 1 or 2 years of age, normal development of the central nervous system diminishes the flexion response, and the toes subsequently move downward. In a positive Babiski response, upper motor neuron dysfuction disrupts the normal plantar cutaneous reflex and the “flexion respinse” re-emerges. Upper motor neuron signs may coexist (e.g: spasticity, weakness, hyperreflexia). In the hyperacute period following upper motor neuron dysfunction, the Babiski response ( as with spasticity and hyperreflexia) may be absent, as it may take hours or days for these signs to emerge.
SIGN VALUE
The Babiski sign is an upper motor neuron sign. It may be absent initially in the hyperacute period following upper motor neuron dysfunction. Sensitivity: 45%, speccificity: 98%, Positive LR 19.0, Negative LR: 0.6
(McGee S, Evidence Based Physical Diagnosis, 2nd edition)
Note: In infant, Babinski positive in a healthy newborn
Hoffmann’s reflex: The test involves tapping the nail or flicking the terminal phalanx of the middle or ring. The positive response in seem with flexion of the terminal phalanx of the thumb.